If you are a 3D artist, you can make pretty good game demos without knowing any coding, but if you know a programmer, you can really make some cool demos!
The games have to use the new Bullet physics engine in a major way, other than that, anything goes.
Here is some more info on the competition.
http://www.continuousphysics.com/mediawiki-1.5.8/index.php?title=Blender_Game_Contest
Blender is totally free to use ( and open sourced ), so you can download the latest version ( PC, Mac, Linux, even a Pocket PC version! ) from here ( RC2 – release candidate 2, a new build is going to be released in the next few weeks )
http://download.blender.org/release/Blender2.42/
Here are a few screenshots from the latest version of the Blender GE, they look sh1t hot!
http://blenderartists.org/forum/showthread.php?t=70203
http://blenderartists.org/forum/showthread.php?t=70776
I’m currently putting together a brief article on how to use the Blender GE, I’ll post it when it’s online.
Regards…
Mal